PostgreSQL also known as Postgres, is a free and open-source relational database management system (RDBMS) emphasizing extensibility and SQL compliance.
PostgreSQL features transactions with ACID properties, automatically updatable views, materialized views, triggers, foreign keys, and stored procedures.
It is designed to handle a range of workloads, from single machines to data warehouses or Web services with many concurrent users.
PostgreSQL manages concurrency through multiversion concurrency control (MVCC), which gives each transaction a "snapshot" of the database, allowing changes to be made without affecting other transactions.
PostgreSQL provides an asynchronous messaging system that is accessed through the NOTIFY, LISTEN and UNLISTEN commands.
PostgreSQL includes built-in support for regular B-tree and hash table indexes, and four index access methods: generalized search trees (GiST), generalized inverted indexes (GIN), Space-Partitioned GiST (SP-GiST) and Block Range Indexes (BRIN).
Official website : https://www.postgresql.org/